1. Field of the Invention
The invention relates to a front passenger seat air bag apparatus.
2. Description of the Related Art
U.S. Pat. No. 7,347,450 describes a front passenger seat air bag apparatus with a variable vent hole, in which a vent hole that is open when an air bag begins to inflate is closed by a strap as the air bag inflates. With this front passenger seat air bag apparatus, the strap is connected to the vent hole and a lower portion of the air bag that is toward the rear of the vehicle when the air bag is inflated.
When a vehicle that is equipped with a front passenger seat air bag apparatus is involved in a frontal collision, the passenger seated in the front passenger seat is restrained by an air bag that inflates and deploys between the passenger and the instrument panel. In this case, when a passenger seated in the front passenger seat is not wearing a seatbelt in a country or region where it is not mandatory to wear a seatbelt in the front passenger seat, inertia will cause the entire body of the passenger to move forward relative to the vehicle, so the entire upper body of the passenger will strike the air bag. The structure described in the related art above is designed so that when the entire upper body of the passenger strikes the air bag in this way, the strap that is connected to the lower rear portion of the air bag will go slack and the vent hole will open due to the rise in internal pressure from restraining the passenger.
However, when a passenger seated in the front passenger seat is wearing a seatbelt, the lower portion of the upper body of the passenger is inhibited from moving forward relative to the vehicle. Therefore, with the structure of the related art described above, the strap is less apt to go slack so the vent hole will not open as easily.